The invention relates to electromechanical locking mechanisms in general and in particular to electromechanical locking mechanisms having a rotary lock bolt.
In U.S. Pat. No. 5,134,870 to Uyeda et al, there is illustrated and described an electromagnetic locking mechanism including a rotary lock bolt governing the locking and unlocking of a door via a handle driven bolt works mechanism having a bolt works member reciprocable between first and second operative positions respectively corresponding to locked and unlocked states of the door. Alternative implementations of the electromagnetic locking mechanism are required, each suitable for use with either one or the other of a clockwise and a counterclockwise operative bolt works mechanism.
The rotary lock bolt is urged into a normally protruding locking position by a biasing spring whereby it is transversely disposed in the path of the bolt works member which slidingly abuts there against to forciby rotate the former to a substantially retracted unlocking position on the latter""s displacement from its first operative position to its second operative position. To prevent an unauthorized opening of the door, rotation of the rotary lock bolt is stopped by means of a solenoid armature which is retracted on entry of an access code via a digital keypad entry device. To avoid undue shear stress on the solenoid armature during an attempted unauthorized opening i.e. when the solenoid armature is extended, the rotary lock bolt is provided with a safety notch which engages a safety key after the rotary lock bolt rotates slightly about its point of contact with the solenoid armature.
In operation, the biasing spring undesirably presents an increasing resistance from the initial contact between the bolt works member and the rotary lock bolt until the free passage of the bolt works member to its second operative position. Secondly, there is undesirable play in the bolts works mechanism before engagement between the safety notch and safety key. Lastly, engagement between the safety notch and the safety key may leave the bolt works mechanism inoperable in a so-called xe2x80x9cdeadlock statexe2x80x9d due to the biasing spring not returning the rotary lock bolt to its normally protruding locking position on the return displacement of the bolt works member to its first operative position.
In accordance with a first aspect of the present invention, there is provided an electromagnetic locking mechanism comprising:
(a) a rotary lock bolt rotatably reciprocable between a normally protruding locking position and a retracted unlocking position on a forced rotation thereof by an external opening force;
(b) a lock bolt urging member in continuous abutting engagement with said rotary lock bolt and linearly reciprocable between a normally outwardly biased position for urging said rotary lock bolt to said normally protruding locking position and a retracted position on said forced rotation of said rotary lock bolt; and
(c) a blocking member reciprocable between a blocking position in said normally protruding locking position of said rotary lock bolt and an unblocking position for respectively preventing and enabling a rearward displacement of said lock bolt urging member from said normally outwardly biased position to said retracted position on said forced rotation of said rotary lock bolt.
An electromagnetic locking, mechanism of the present invention is adapted for installation in a conventional manner in safes, vaults, strong rooms and the like having a handle driven bolt works mechanism as described hereinabove, namely, with a bolt works member for forcibly rotating the rotary lock bolt from its normally protruding locking position to its retracted unlocking position on entry of an access code. In a simplified construction, an electromagnetic locking mechanism of the present invention is suitable for use with only one type of operative bolt works mechanism, namely, either a clockwise or a counterclockwise operative bolt works mechanism. In a modified construction of an electromagnetic locking mechanism of the present invention, the positions of the rotary lock bolt and bolt lock urging member are interchangeable such that the electromagnetic locking mechanism can be installed in either a clockwise or a clockwise bolt works mechanism. An electromagnetic locking mechanism of the present invention as can other constructions of electromagnetic locking mechanisms with rotary lock bolts, for example, as illustrated and described in the aforementioned U.S. Pat. No. 5,134,870 can be preferably adapted for installation in typically smaller safes and the like which are locked and unlocked directly by a handle operated lock.
The rotary lock bolt has a cam surface in continuous abutting engagement with an abutment surface of the lock bolt urging member which is inclined with respect to the latter""s direction of linear reciprocation. The lock bolt urging member is preferably normally outwardly urged by a biasing spring acting against a trailing portion thereof and compressible in a direction co-directional with the lock bolt urging member""s rearward displacement. A solenoid armature constituting a blocking member of the stopping means is preferably linear reciprocable in a direction perpendicular to the lock bolt urging member""s linear reciprocation. The solenoid armature is operatively associated with a lock bolt arresting member which is integrally formed with the lock bolt urging member in the simplified construction of the electromagnetic locking mechanism of the present invention and which is detachable therefrom in the modified construction of the electromagnetic locking mechanism of the present invention adaptable for use in either a clockwise or a counter clockwise operative bolt works mechanism. The solenoid armature is selectively reciprocable between an outwardly biased blocking position in the normally outwardly biased position of the lock bolt urging member and a retracted unblocking position enabling the rearward displacement of the lock bolt urging member. The solenoid is preferably a magnetically latched solenoid whilst the code entry means is preferably implemented by the data receiving means as described in PCT/IL98/00105. An electromagnetic locking mechanism of the present invention fitted with long life batteries can have a useful life of several years during which it can is be operated many thousand of times.
In operation, the solenoid armature is retracted on entry of an access for sufficient time for an external opening force applied to the rotary lock bolt to compress the biasing spring during the rearward displacement of the lock bolt urging member from its normally outwardly biased position to its retracted position. By virtue of the camming action gradually acting over a longer arm as the rotary lock bolt is gradually forced to its retracted unlocking position, the force required to compress the biasing spring correspondingly gradually becomes less. The solenoid armature presents a virtually immediate positive blocking action to an attempted unauthorized opening and also precludes the possibility of a deadlock situation from arising. In an attempted unauthorized opening of a door, the force applied against the rotary lock bolt acts internal supporting structures thereby considerably reducing the force directly applied against the solenoid armature.
In accordance with a second aspect of the present invention, there is provided an electromagnetic locking mechanism comprising:
(a) a rotary lock bolt rotatably reciprocable between a normally protruding locking position and a first retracted unlocking position on a forced rotation thereof by an external opening force;
(b) a handle operated carriage linearly reciprocable between outward and inward positions for selectively displacing said rotary lock bolt between said normally protruding locking position and a second retracted unlocking position; and
(c) a blocking member reciprocable between a blocking position in said normally protruding locking position of said rotary lock bolt and an unblocking position for respectively preventing and enabling a rearward displacement of said carriage from said outward position to said inward position.